pl/sql-native dynamic sql

To process dynamic SQL statements, you use EXECUTE IMMEDIATE or OPEN-FOR, FETCH,

and CLOSE statements. EXECUTE IMMEDIATE is used for single-row SELECT statements, all

DML statements, and DDL statements. OPEN-FOR, FETCH, and CLOSE statements are used

for multirow SELECTs and reference cursors.

 

Part One: execute immediate

EXECUTE IMMEDIATE dynamic_SQL_string

[ INTO defined_variable1, defined_variable2, ...]

[ USING [IN | OUT | IN OUT] bind_argument1, bind_argument2,

...][{ RETURNING | RETURN } field1, field2, ... INTO bind_argument1,

bind_argument2, ...] 

 

DECLARE
    sql_stmt  VARCHAR2 ( 100 );
    plsql_block  VARCHAR2 ( 300 );
    v_zip  VARCHAR2 ( 5 ) : =   ' 11106 ' ;
    v_total_students  NUMBER ;
    v_new_zip  VARCHAR2 ( 5 );
    v_student_id  NUMBER  : =   151 ;
BEGIN
     --  Create table MY_STUDENT
    sql_stmt : =   ' CREATE TABLE my_student  ' ||
                             ' AS SELECT * FROM student WHERE zip =  ' || v_zip;
     EXECUTE  IMMEDIATE sql_stmt;
    
     --  Select total number of records from MY_STUDENT table
     --  and display results on the screen
     EXECUTE  IMMEDIATE  ' SELECT COUNT(*) FROM my_student '
     INTO  v_total_students;
    
    DBMS_OUTPUT.PUT_LINE ( ' Students added:  ' || v_total_students);
    
     --  Select current date and display it on the screen
    plsql_block : =   ' DECLARE  '   ||
                                     '  v_date DATE;  '   ||
                                     ' BEGIN  '   ||
                                     '  SELECT SYSDATE INTO v_date FROM DUAL;  ' ||
                                     '  DBMS_OUTPUT.PUT_LINE (TO_CHAR(v_date,
                                     '' DD-MON-YYYY '' ))
                                    ; ' ||
                                     ' END; ' ;
     EXECUTE  IMMEDIATE plsql_block;
     --  Update record in MY_STUDENT table
    sql_stmt : =   ' UPDATE my_student SET zip = 11105 WHERE student_id = :1  ' ||
                             ' RETURNING zip INTO :2 ' ;
     EXECUTE  IMMEDIATE sql_stmt USING v_student_id RETURNING  INTO  v_new_zip;
    DBMS_OUTPUT.PUT_LINE ( ' New zip code:  ' || v_new_zip);
END ;

 

 

 

NOte that:
A  CREATE TABLE statement is a data definition statement(DDL). Therefore, it cannot accept any  bind
arguments. Following example will generate error:
DECLARE
    sql_stmt  VARCHAR2 ( 100 );
    v_zip  VARCHAR2 ( 5 ) : =   ' 11106 ' ;
    v_total_students  NUMBER ;
BEGIN
     --  Drop table MY_STUDENT
     EXECUTE  IMMEDIATE  ' DROP TABLE my_student ' ;
     --  Create table MY_STUDENT
    sql_stmt : =   ' CREATE TABLE my_student  ' ||
     ' AS SELECT * FROM student  ' ||
     ' WHERE zip = :zip ' ;
     EXECUTE  IMMEDIATE sql_stmt USING v_zip;
     --  Select total number of records from MY_STUDENT table
     --  and display results on the screen
     EXECUTE  IMMEDIATE  ' SELECT COUNT(*) FROM my_student '
     INTO  v_total_students;
    DBMS_OUTPUT.PUT_LINE ( ' Students added:  ' ||  v_total_students);
END ; 

 

DECLARE

*

ERROR at line 1:

ORA-01027: bind variables not allowed for data definition operations

ORA-06512: at line 12 

 

 

 

 

DECLARE
    sql_stmt  VARCHAR2 ( 100 );
    v_zip  VARCHAR2 ( 5 ) : =   ' 11106 ' ;
    v_total_students  NUMBER ;
BEGIN
     --  Create table MY_STUDENT
    sql_stmt : =   ' CREATE TABLE my_student  ' ||
     ' AS SELECT * FROM student  ' ||   ' WHERE zip = ' ||  v_zip;
     EXECUTE  IMMEDIATE sql_stmt;
     --  Select total number of records from MY_STUDENT table
     --  and display results on the screen
     EXECUTE  IMMEDIATE  ' SELECT COUNT(*) FROM :my_table '
     INTO  v_total_students
    USING  ' my_student ' ;
    DBMS_OUTPUT.PUT_LINE ( ' Students added:  ' ||  v_total_students);
END ;


When  run, this example causes the following error:
DECLARE
*
ERROR at line  1 :
ORA - 00903 : invalid  table  name
ORA - 06512 : at line  13

This example causes an error because you cannot pass names  of schema objects to dynamic SQL
statements as bind arguments.  To  provide a  table  name at runtime, you need  to  concatenate this
example  with  the  SELECT  statement:

EXECUTE IMMEDIATE 'SELECT COUNT(*) FROM '||my_table
INTO v_total_students;

 

Notice: The semicolon added to the SELECT statement is treated as an invalid character when the statement

is created dynamically. A somewhat similar error is generated when a PL/SQL block is

terminated by a slash: 

 

Part Two： OPEN-FOR, FETCH, and CLOSE Statements

below is an example :

 DECLARE

    TYPE student_cur_type  IS  REF  CURSOR ;
    student_cur student_cur_type;
    v_zip  VARCHAR2 ( 5 ) : =   ' &sv_zip ' ;
    v_first_name  VARCHAR2 ( 25 );
    v_last_name  VARCHAR2 ( 25 );
BEGIN
     OPEN  student_cur  FOR
     ' SELECT first_name, last_name FROM student  ' ||   ' WHERE zip = :1 '
    USING v_zip;
    
    LOOP
         FETCH  student_cur  INTO  v_first_name, v_last_name;
         EXIT   WHEN  student_cur % NOTFOUND;
        DBMS_OUTPUT.PUT_LINE ( ' First Name:  ' || v_first_name);
        DBMS_OUTPUT.PUT_LINE ( ' Last Name:  ' || v_last_name);
     END  LOOP;
    ...